In recent years, in image pickup apparatus such as video cameras, the apparatus have been advanced with reduction in size and weight, high-multiplification zooming, and moreover multi-function, so that product development is undergoing in which the optical zoom and electronic zoom functions are interlocked. Also, as users have spread over from children to the old as well as conventional enthusiasts, screen blurs due to hand blurs are generated, and there have been marketed image pickup apparatus provided with a motion correction circuit using electronic zoom function.
A conventional motion corrector device using the electronic zoom function is shown in, for example, TV society technical report Vol. 11, No. 3 (May. 1987).
The conventional motion correction circuit having an electronic zoom function is described below.
An input signal is converted into a digital signal by an A/D converter and fed to a motion vector detector circuit and a memory circuit, and in the motion vector detector circuit video signals of two fields are compared to detect a motion vector, and in a memory control circuit using the motion vector to obtain a stub signal corrected for hand blurs from the memory circuit, and a memory output signal is formed into a normal video signal by an interpolation circuit which is controlled by an interpolation control circuit and is converted into an analog signal by a D/A converter circuit.
In this way, a motion vector is detected from two-field video signals, and hand blurs are corrected by the interpolation function.
As another example of the conventional image pickup apparatus having a horizontal line interpolation function, there is listed, e.g., "An image pickup apparatus" of U.S. Pat. No. 4,951,125 (registered on Aug. 21, 1990), which was filed by the present applicant and registered.
The conventional motion correction circuit having an electronic zoom function is described below.
The above conventional example comprises: a solid state image pickup element; an image pickup element drive circuit for controlling the transfer and halt of vertical transfer (scanning) of the solid state image pickup element with a control signal (denoted by CTL1); a switching unit for apportioning an output signal SO of the solid state image pickup element according to a control signal (denoted by CTL2) to a first line memory M1 through an nth line memory Mn (n.gtoreq.3, where n is an integer); a selector for selecting output signals of m lines out of the line memories M1 through Mn (2.ltoreq.m&lt;n, where m is an integer) according to a control signal (denoted by CTL3); one or a plurality of multipliers for multiplying output signals S1 through Sm of the selector with weighting signals W1 through Wm, respectively; an adder for adding output signals of the multipliers; and a control signal generator circuit for generating the control signals CTL1, CTL2, CTL3, and W1 through Wm, wherein the switching unit is controlled in such a way that, when a signal stored in the line memory Mx (1.ltoreq..times..ltoreq. n, where x is an integer) which remains after the selection by the selector is the oldest signal out of the line memories M1 through Mn, vertical transfer (scanning) of the solid state image pickup element is effected so that a new one-line sin SOnew is generated and then the signal SOnew is written into the line memory Mx.
In the image pickup apparatus with an interpolation function as described above, there has been a problem that frequency response characteristics may deteriorate in the interpolation process and therefore affect the image quality.